Top feeding mechanisms for sewing machines



May 8, 1934. H. F. GRUMAN TOP FEEDING MECHANISM FOR SEWING MACHINES Original Filed Oct. 29, 1924 2 Sheets-Sheet l Gttorneg May 1934- H. F. GRUMAN 1,958,337

TOP FEEDING MECHANISM FOR SEWING MACHINES Original Filed Oct. 29, 1924 2 Sheets-Sheet 2 Patented May 8, 1934 UNITED STATS TENT FFICE TOP FEEDING MECHANISMS FOB SEWING MACHINES Horace F. Qruman, St. Louis. Mo., assignor to Lew s Invisible Stitch Machine Company, St. Louis, Mo, a corporation of Maine 9 Claims.

This invention relates generally to sewing machines and has for its object to provide a novel four motion top feed mechanism of a particularly durable and compact nature and which is so constructed and arranged as to automatically adapt itself to the feeding of materials of varied thicknesses, thus assuring smooth and efficient feeding action under varying conditions of operation. This application is a division of my application Serial No. 746,676, filed October 29, 1924, patented March 11, 1930, No. 1,750,041.

With the above and other objects in view which will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawings.

In the drawings:

Figure 1 is an end elevation illustrating the feeding mechanism,

Figure '2 is a vertical section taken on the line 22 ofFigure 1,

Figure 3 is a vertical section taken on the line 33 of Figure 1, the feed bar collar being shown out of contact with the sleeve abutment shoulder indicating a dwell period during which the feed dog remains in contact with the work prior to lifting engagement of the shoulder with said collar,

Figure 4 is a detail side elevation illustrating the invention,

Figure 5 is a fragmentary rear elevation of parts shown in Figure l, and

Figure 6 is a detail face view of the feed lift efiecting bell crank lever.

Like reference numerals designate corresponding parts throughout the several figures of the drawings.

In the drawings 5 designates the overhanging 40 arm of a sewing machine. The arm 5 carries the usual sewing head 6 at its free end, said arm and head being hollow at '7 and 8 respectively for purposes that will become evident as the description progresses.

A shaft 9 is rotatably mounted in bearings 10 located in the arm 5, one of said bearings being disposed in the partition wall 11 which divides the hollow portions of the arm and head as shown in Figure 2 of the drawings.

The usual needle bar is indicated at 12 and is vertically reciprocated by the customary crank and link connections 13 with the shaft 9. The bar 12 carries the needle or needles 14.

A work support or throat plate is indicated at 15 and a presser foot 16 cooperates with this element in the usual manner. The foot 16 is carried at the lower end of a presser bar or shank 1"? which is vertically slidable in the sewing head 6.

The presser foot extends a distance in advance of and to the rear of the needles and is slotted as at 18 to accommodate the upper feed dogs. Customary presser foot lifting and hold down devices are indicated at 19 and 20 respectively. Top feed dogs or fingers 21 are provided and are carried by the feed bar shank 22 to which reciprocatory and oscillatory movements are transmitted to eifect the four motion lift and travel movements of the feed dogs in a manner soon to be described. The feed dogs 21 are directly attached to the free end of a support arm 23 which is laterally bent as at 24 and extended in a manner for positioning said dogs in advance of the needles and directly in the stitch line, the other end of said arm being directly connected with the shank 22. For this purpose the free end of the arm 23 is slotted as at 25, the dogs being secured in the slot by employment of a clamp screw 26.

In this manner the angularity of the feed dogs 21 with respect to the arm 23 may be adjusted.

The feed bar shank 22 is vertically slidable in a sleeve 27 which is in turn slidable in and oscillatable with a guide block 28 having pivotal mounting on a stub shaft 29 mounted in the sewing head. This sleeve 2'7 has an enlarged bore 39 to receive a spring 31 which surrounds the shank 22 and abuts at one end a collar 32 fixed on said shank, and at the other end, a tension adjuster and bearing sleeve 33. The spring 31 serves constantly to impart a yielding downward pressure upon the feed dogs 21 and this pressure may be suitably varied by rotating the sleeve 33. In this manner a cushion mounting is provided for the feed dogs which will serve to automatically compensate for variations in the thicknesses of materials being operated upon as well as to relieve shock and prevent breakage.

The shank 22, the carrying sleeve 27, and the enclosed spring 31 and abutment collar 32, together comprise the feed bar.

In order to provide for the lifting and lowering movement of the feed dogs, the sleeve 27 is provided with a lug 34 which extends into a transverse horizontally disposed slot 35 formed in the horizontal arm 36 of a bell crank lever. The lever is pivoted or rockably mounted at 37 in the head 6 and includes a vertical arm terminating in a fork 38 which embraces an eccentric 39 secured 1m on the shaft 9 inside the head 6. As the eccentric is rotated, it will rock the bell crank to and fro to effect an alternate lifting and lowering of the sleeve 27 and the feed dogs carried thereby.

I will now describe the means for effecting the travel and retractile movement of the feed dogs. A lever is pivoted intermediate its ends as at 41 to the head 6 and has its lower end link connected as at 42 to the feed clog carrying arm 23. The upper arm of the lever 40 has a slot 43 engaged by a block 44 arranged to be clamped in the slotted arm of a bell crank lever 45 by an adjustable nut 46.

The bell crank lever 45 is pivoted at 47 in the head 6 and has its other arm 48 forked and extended into the arm 5 where it embraces an eccentric 50 secured upon the shaft 9. Thus as the eccentric 50 is rotated, it will rock the bell crank lever 45 and the rocking lever 40 and thereby impart alternate thrusts and retractions to the link 42 to effect the feeding and retracting movements of the feed dogs 21.

With the mechanism described the feed dogs 21 are given a movement along the slotted presser foot and also up and down movements so as to provide the desired four motion feeding action, the eccentric 39 and its connections effecting the up and down movements, while the eccentric 50 s and its connections provide the forward and backward movements. The feed can be varied by adjustment of the block 44.

It should be understood that the full vertical stroke of the sleeve 27 need not be utilized to impart movement to the shank 22. This shank may be elevated slightly by the work beneath it so that the collar 32 will not follow the abutment shoulder of the sleeve 2'7 to the lower limit of its travel, thus providing a clearance between the sleeve 1 abutment shoulder and the collar as shown in Figure 3. Such clearance will have to be taken up during upward travel of the sleeve 27 before lifting movement will be imparted thereby to the shank 22, thereby causing the feed dog to dwell on the work.

It will be observed that the eccentric and bell crank connections are disposed in compact and balanced relation at respective sides of the bearing 10 in the division wall 11. Also, that the bell crank 3638 is directly connected to the sleeve. These features of construction and arrangement contribute greatly to the simplicity, compactness, and balanced positive operation of the machine parts described herein.

It will be noted further that the feed bar shank 22 is afforded a bearing in the sleeves 27, 33. In this manner a notably long bearing is provided for the shank which will practically eliminate all lost motion and tendencies to bind.

It is of course to be understood that the details of structure and arrangements of parts may be variously changed and modified without departing from the spirit and scope of my invention.

I claim:

1. In a sewing machine, a four-motion top feed mechanism including a vertically reciprocable and pivotally mounted feed bar comprising telescopic spring cushioned casing and shank elements, a rotary shaft, an eccentric rotatable with the shaft, a rockably mounted bell crank lever having one arm engaged by said eccentric to receive rocking motion therefrom, a slot and pin connection between the other arm of said lever and the casing element, and means to impart oscillatory movement to said feed bar.

2. In a sewing machine wherein is provided an overhanging arm and a hollow sewing head at the end thereof, a rotary shaft mounted in said arm and projecting into said head, a vertically reciprocable and pivotally mounted feed bar comprising telescopic spring cushioned casing and shank elements, an eccentric secured upon the projected end of the shaft, a bell crank mounted to rock in a plane transversely of the axis of the shaft and having one arm in engagement with the eccentric to receive rocking motion therefrom, the other arm of said bell crank being directly connected with the casing element by a pin and slot connection, and means to impart oscillatory movement to said feed bar.

3. In a sewing machine, a four motion top feed including a vertically reciprocable and pivotally mounted feed bar comprising a feed dog carrying shank, a sleeve to telescopically receive said shank and having a bearing bore and an enlarged bore forming an abutment shoulder, a spring in the enlarged bore, an abutment secured to the shank and opposed by the spring to be yieldingly held against the abutment shoulder, a tension adjusting sleeve threaded into the first mentioned sleeve and abutting the spring and provided with a bore to receive the shank, and means to impart reciprocatory and oscillatory movement to the feed bar.

4. In a sewing machine, a four motion top feed including a vertically reciprocable and pivotally mounted feed bar comprising a feed dog carrying shank, a sleeve to telescopically receive said shank and having a bearing bore and an enlarged bore forming an abutment shoulder, a spring in the enlarged bore, an abutment secured to the shank and opposed by the spring to be yieldingly held against the abutment shoulder, a tension adjusting sleeve threaded into the first mentioned sleeve and abutting the spring and provided with a bore to receive the shank, a pivotally mounted block having a bearing bore to slidably receive the first mentioned sleeve, and means to impart reciprocatory and oscillatory movements to the feed bar.

5. In a sewing machine wherein is provided a hollow overhanging arm and a hollow sewing head carried thereby, said arm and head hollows being divided by a partition wall, a rotary shaft mounted in the arm and projecting into the head and having rotating bearing in the partition wall, an eccentric secured upon the shaft at each side of the partition wall, a four motion top feed including a vertically reciprocable and pivotally mounted feed bar, a feed dog carried by the bar, a transversely rockable bell crank lever mounted in the head and directly engaging the eccentric in the head and the feed bar to impart vertical reciprocations to the latter, and means actuated by the eccentric in the arm to impart feed travel movements to said feed bar.

6. In a sewing machine wherein is provided a hollow overhanging arm and a hollow sewing head carried thereby, said arm and head hollows being divided by a partition wall, a rotary shaft mounted in the arm and projecting into the head and having rotating bearing in the partition wall, an eccentric secured upon the shaft at each side of the partition wall, a four motion top feed including a vertically reciprocable and pivotally mounted feed bar, a vertically reciprocable needle bar, a feed dog carrier secured to the feed bar and extending parallel to the stitching line from the point of connection with the feed bar to a point in advance of the needle bar and including a portion bent laterally and downwardly to a point directly above the stitching line, a feed dog carried by said bent portion, means actuated by the eccentric in the sewing head for imparting lifting and lowering movements to the feed bar, and means actuated by the eccentric in the arm for moving the feed bar about its pivotal mounting for imparting feeding and retracting movements to said feed bar.

7. In a sewing machine wherein is provided a vertically reciprocable needle bar, a four-motion top feed mechanism comprising a vertically reciprocable and pivotally mounted feed bar, a feed dog carrier secured to the feed bar and extending parallel to the stitching line from the point of connection with the feed bar to a point in advance of the needle bar and including a portion bent laterally and downwardly to a point directly above the stitching line, a feed dog angularly-adjustably carried by said bent portion, means to impart lifting and lowering movements to the feed bar, and means for moving the feed bar about its pivotal mounting for imparting feeding and retracting movements to said feed bar.

8 In a sewing machine, a hollow sewing head, a four-motion top feed mechanism including a vertically reciprocable and pivotally mounted feed bar operating in part in the sewing head, a rotary shaft projecting into the sewing head, an eccentric mounted on and rotatable with the portion of the shaft projecting into the sewing head, a bell crank lever rockable about a pivot fixed in the sewing head and having one arm engaged by said eccentric to receive rocking motion therefrom and its other arm directly connected to said bar to impart vertical reciprocation thereto, and means to impart oscillatory movement to said bar.

9. In a sewing machine; a four motion top feed including a vertically reciprocable and pivotally mounted feed bar comprising a feed dog carrying shank, a sleeve to telescopically receive said shank and having a bearing bore and an enlarged bore forming an abutment shoulder, a spring in the enlarged bore, and an abutment secured to the shank and opposed by the spring to be yieldingly held against the abutment shoulder; and means to impart reciprocatory and oscillatory movement to the feed bar including means to vertically reciprocate the sleeve so that the lower limit of sleeve movement will exceed the distance to which the shank can move when engaging work whereby to cause the sleeve abutment shoulder and the shank abutment to become separated and enable the feed dog to dwell on the work during a part of the upward movement of the sleeve.

HORACE F. GRUMAN. 

